A propositional analyst’s assistant

A system (PAN) that is designed to assist both the inexperienced and the experienced user in performing propositional analysis is described. The system is implemented in UCSD Pascal on the Apple II and Apple He microcomputers.     

Why can't we tickle ourselves?

When we tickle ourselves something prevents the sensation being as strong as when someone else does it. It is suggested that the "something" may be: (i) the predictability of the stimulus; (ii) the presence of feedback from the movement of the arm doing the tickling; (iii) the presence of a corollary discharge from the voluntary movement of the tickling arm; (iv) the absence of a social/sexual context. To study these, Ss rated perceived "tickle-strength" in situations where they were tickled: (a) with their eyes closed; (b) with their eyes open; (c) with their own arm doing the tickling, but being moved by someone else; (d) by themselves. One group of Ss was divided into same sex and different sex subject-experimenter pairs. The results showed significant effects of predictability and sensorimotor feedback.     

Study-time of sentences as a function of their specificity and of semantic exploration

In self-paced learning conditions the study-time of sentences is supposed to depend jointly upon the information content of the material and upon its exploration by the subject in the course of learning. In exp. 1 informative content was varied by using sentences constituted either of general or of specific words; study-time was found to be significantly longer for the latter sentences than for the former and the recall performance to be equal. Differential semantic exploration and storage were instigated by presenting in the series either pairs of similar, and thereby contrasted sentences, or isolated sentences. In exp. 2, study-time of the sentences was longer than that of the latter; but the first recall performance recorded with the constrasted sentences was also higher. The divergent effects of the nature of the material and of the activity of the subject upon study-time and recall performance were emphasized.     

Effect of the length of the runs of repetitions on the simple RT-ISI relationship

In a simple RT task the temporal organization of the preparatory processes during a given trial depends upon the time characteristics of the total experimental situation as well as upon the information gathered during one or more previous trials. The present experiment was run in order to determine whether or not these long and short term effects operate independently or interact. The effects of the preceding ISI durations on the simple RT for an ISI 1 (1.5 s) or an ISI 2 (3.0 s) are analysed in 3 experimental conditions differing in the maximum number of successive repetitions (2, 3 or 7) of trials with the same ISI. The results show that the distribution of the preparatory activity during a given trial depends firstly on the number of successive ISIs of the same duration preceding this trial, and secondly on the maximum number of repetitions. An explanation of the subjects' strategy based upon “cost of preparation” is proposed.     

Repetition effect with picture stimuli: Possible implications for clarity

Increasing recognition accuracy with repeated presentations was demonstrated for complex pictorial stimuli (real-world photographs) by accuracy, signal detection, and confidence of decision indicators. Consistent with other research, the effect occurred only for short stimulus durations. The effect occurred for both old and new pictures, the rate of improvement being greater for old than for new pictures. Experiment II utilized focus-degraded stimuli to demonstrate that amount of information artifacts were not responsible for the observed differences between responses to old and new pictures.     

A measurement technique for stability as applied in rifle shooting

A technique is described for the measurement, in the field, of stability and steadiness. Apparatus and method are provided along with suggested scoring procedures.     

Effects of a timing signal on simple reaction time with a rectangular distribution of foreperiods

It was hypothesized that the time course of preparation during a variable interstimulus interval (ISI) of a simple reaction time (RT) experiment was partly determined by the subjective distribution of conditional probabilities of the executive signal (ES). Sixty subjects performed a simple auditory RT task with various ranges of six ISI durations organized in rectangular frequency distributions. In order to give the subjects information about elapsed time during ISI, a recurring time-marking click, the periodicity of which was varied, was introduced during the ISI in one of the three series of trials each subject performed. A strong decreasing RT--ISI relationship was observed supporting the main hypothesis. However, a clear increase of mean RT over all ISIs combined, was also found. Because these two mixed effects were greatest when the click intervened at the possible times of ES occurrence only, three functions of time-information given by the click are discussed: (a) a reduction of the usual increase of time estimation error with increased ISI; (b) an increase of the subjects knowledge of the ISI range resulting from the discontinuity of the time-marking click which makes easier a discrete time-intervals numbering process; (c) a change of the simple-RT task into a discrimination task.     

Artificial intelligence and animal psychology: A response to Boden, Margolis and Sloman

We propose the elements of an epistemological framework in which to situate the fundamental problem of ascribing mentalistic concepts to animals and machines that is posed by Margaret Boden's, Aaron Sloman's and Joseph Margolis' discussion of artificial intelligence and animal psychology.     

Emerging from imaginary time

Recent models in quantum cosmology make use of the concept of imaginary time. These models all conjecture a join between regions of imaginary time and regions of real time. We examine the model of James Hartle and Stephen Hawking to argue that the various no-boundary attempts to interpret the transition from imaginary to real time in a logically consistent and physically significant way all fail. We believe this conclusion also applies to quantum tunneling models, such as that proposed by Alexander Vilenkin. We conclude, therefore, that the notion of emerging from imaginary time is incoherent. A consequence of this conclusion seems to be that the whole class of cosmological models appealing to imaginary time is thereby refuted.We would like to thank Quentin Smith for helpful comments on an carlier version of this eassy. Read Guy gratefully acknowledges support from the M.J. Murdock Charitable Trust.